Direction finder



Nov. 29,1949 H. G. BuslGNlEs 2,489,253

DIRECTION FINDER Filed Aug. 6, 1945 3 Sheets-Sheet 1 a.: 60N/0M A700/0 fece/vez I /15 J 15 ac. I) i I? l i ,4MM/H5@ Maro/a j "V 74 spfso l m :mmm i 8 /.S/ i J0 I l i l l l l l l l l l I l g L IN V EN TOR.

ATTOREY Nov. 29, 1949 Filed Aug. 6, 1945 H. G. BUSIGNIES DIRECTION FINDER o. f'. 60N/annex molo Recs/veg J Home SPEED L CONTUL 5 3 Sheets-Sheet 2 INVEN TOR. Hf/V/ 50676/1055 ATTOJEEY H. G. BUSIGNIES DIRECTION FINDER Novi, 29, 1949 Filed Aug. 6, 1945 fm @es Y 3 Sheets-Sheet .'5

I N V EN TOR. HENA/ 6. BUS/60755 VBY Patented Nov. 29, 1949 vmauc'rron FINDER Henri G. Busignies, Forest Hills, N. Y., asslgnor to Federal Telephone and Radio Corporation, New i York, N. Y., a corporation of'Delaware Application August 6, 1945, Serial No. 609,216

Claims. (Cl. 343-118) This invention relates to direction finder systems and `more particularly to systems of the type employing a rotatable directively sensitive pick-up.

A principal object of the invention is to provide a direction finder system having an increased degree of flexibility as regards the duration of the picked-up direction nder signals and their translation into a resultant visual indication.

Another principal object is to provide a direction nder system of the directionally sensitive rotatable pick-up type, in conjunction with a visual indicator of the integrating type and an intervening storage device which makes a nonvisual stored record of the successive elements of the polar diagram of the pick-up.

A feature of the invention relates to a direction iinder system employing a rotatable direction finder antenna and a visual indicator of the integrating type, together with a special form of storage device having a commutating arrangement synchronized with the antenna radiation, the indicator also having a beam-deiiecting control which is synchronized with said antenna.

A further feature relates to the production of a-relatively persistent visual indication notwithstanding that the original direction finder signals are of momentary duration.

A still further feature relates to the novel organization and arrangement of parts constituting an improved direction finder system employ ing an integrating indicator.

Other features and advantages will become apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing,

Fig. 1 represents a preferred embodiment of the invention.

Fig. 2 represents an alternative embodiment.

Fig. 3 is a modification of Fig. 1.

In systems employing rotatable direction-finder loop antennae, it very frequently happens that the signals from the distant source to be located. are radiated for only a short or momentary interval. It is necessary with certain systems to subject the loop to a considerable number of rofor only momentary intervals. With an arrangement accordingto the invention, it is possible to provide the operator of the direction-finder equipment an appreciable time margin in order to read the bearing of the distant source subsequent to the picking up of the direction nder signals. Furthermore, it is highly desirable to produce an indication which is a substantially true representation of the actual polar diagram of the field intensity around the loop as the latter, is rotating.

There are shown in the drawing, two embodiments of the invention, for achieving the above desired advantages.

Referring to Fi'g. l, there is shown a rotatable direction-finder loop antenna I, which is connected to any well-known goniometer control and commutating mechanism 2, for producing signals which correspond to the signals picked up by the loop. Loop I is continuously rotated by means of a suitable driving motor 3, through transmission gearing 4, and preferably motor 3 is closely controlled as to speed by any wellknown speed control device or circuit 5. The signals from the goniometer 2 are amplified and detected in any well-known form of directionfinder radio receiver 6, and the signals rom the receiver 6 are applied to a distributor member or brush 1. Brush I is in the form of a conductive plate having appreciable area so as to act as an electrostatic coupling to a series of spaced condenser plates 8, which are suitably mounted at equal radial distances on and around a rotatable shaft 9. Each of the condenser plates 8 is connected to ground I0 through an individual RC combination comprising condenser I I and parallel adjustable resistance I2. Each of the RC combinations acts therefore as a storage element for the direction-finder signals which are applied by means of condenser plate 1. The condensers Il and the associated resistors I2 can be provided so as to have a very quick charging path through the output circuit of the receiver and a slower discharging path through the input circuit of amplier I5. The plates 8 are adapted to be rotated as a unit past the stationary coupling element 'I and in slightly spaced relation thereto so that the coupling is by space induction. For the purpose of feeding the stored signals to the indicator part of the system, another coupling element I3 similar to member l is provided. Element I3 may be mounted at any desired relation around the periphery of the rotating members 8 and with respect to the member 1 so as to provide any predetermined time aseaaes delay between the intervals of charge and dischar e.

It gwlll be understood of course, that the invention is not limited to a. rotating commutator with stationary coupling devices 1 and I8. If desired, the plates 8 may be stationary and the members 1 and I3 can be mounted in proper spaced relation and rotated as a unit. In any event, the relative rotation of the plates 8 and the members 1 and I3, is synchronized with the rotation oi' loop I, for example by being driven from the motor 3 as indicated bythe dotted line. The coupling member I8 is connected to a relatively high resistance Il such as a grid leak resistor. The stored voltages on condensers II are then applied to a D. C. amplifier I5 of any well-known construction, whose ampliiled D. C. output is connected through a pair of eld coils I6, I1, which likewise are adapted to be rotated as a unit in synchronism with the loop I as indicated by the dotted line connection to motor 8. The coils I8 and I1 may be of any construction and arrangement well-known in the cathode-ray tube art and are mounted for example around the neck portion I8 of a cathode-ray tube oscilloscope, so as to subject the electron beam I8 to a rotary scanning trace over the fluorescent screen 20 of the oscilloscope. The deilection of the beam I9 will therefore be proportionate to the charge on each of the condensers II and the angular length of each section of this trace will be determined by the duration of contact between the member I3 and each of the plates 8 in suc` cession. In other words, if the polar diagram around the loop I is in the shape, for example, of a cardioid, then as the iield coils I6, I1, are rotated in synchronism with the loop I, and since they are energized by D. C. signals proportionate to the polar diagram, the trace envelope as it appears upon the screen 20 will be a similar cardioid by means of which the operator can directly determine the bearing of the distant source.

While Fig. 1 shows a commutator or distributor comprising 8 segments, it will be understood that a greater or less number may be employed depending upon the neness of resolution desired in the trace on the screen 20. If the eld pattern of the loop I is a true cardioid, 8 segments and 8 storage elements II--I2 aresuicient to give a satisfactory cardioid trace on the screen 20. Consequently, by adjusting the charging time constant of each of the condensers I I', these condensers may be given a very rapid charge corresponding to a momentary existence of the ileld acting on antenna I`, and a relatively slow discharge can be provided thus providing the operator with a sumcient time interval to determine from the reproduced field pattern on the screen 20, the bearing of the momentary radiating source.

Fig. 2 shows a modiiication of Fig. 1, wherein parts corresponding to those of Fig. 1 bear the same designation numerals. In this embodiment, the cathode-ray tube is provided with a series of deector plates 2l, equal in number to the number of plates 8 of the distributor. Each of the distributor plates 8 is directly connected to a corresponding one of the deflector plates 2I. This avoids the necessity of employing a separate rotating deiiecting eld such as that provided by the coils I6 and I1 of Fig. 1, and resuits in the production of a trace 22 on the cathl ode-ray tube screen 20 which is a substantial duplicate of the polar diagram of the antenna 4 I with respect to the radiation from ther distant source to be located.

If the polar diagram. instead of being a cardioid, is a ngure-of-eight, it is necessary that the relative location between the brushes 1, I8, Fig. l, and the distributor segments 8, be twice the rotational speed of the antenna' I. In the case of a ilgure-of-eight diagram, it is not necessary that the discharging of the condensers II be at twice the rate oi radiation oi the antenna I since it is necessary only to make sure that the charging of the condensers I'I is at twice the rotational speed of the antenna. In fact, it is not necessary that the member Il maintain any fixed space relation with member1. The rotation ofW the cathode-ray tube beam I8 should however be synchronous with the rotation of the discharging member I8. With this arrangement, it is preferable to make the plates 8 stationary and to rotate the members 1 and Il. member 1 being driven in locked synchronism with the antenna I, whereas the member I8 may be driven at any desired speed. In that event, the iield coils I8 and I1 instead vof being driven in synchronism with member 1 will be driven in synchronism with member Il.

In the case of a true cardioid field diagram pattern, it is possible to produce a satisfactory cardioid trace merely by using a set of four RC storing networks as shown in Fig. 3, and these storing networksare connected respectively to four individual commutator segments 8. This permits the use of a conventional four-plate deflector cathode-ray tube where the plates are located symmetrically around the axis of rotation of the cathode-ray beam. However, these beam deiiector plates 2l are connected directly to respective condensers II. Consequently, it is not necessary to employ a separate brush or coupling element corresponding to element I3 (Fig. 1).

Instead of arranging the segments 8 in a complete circle. they may be arranged in a half circle and another brush or coupling member 24 can be connected in parallel with member 1. It will be understood of course, that the invention is not limited to the use of a capacity coupling to the commutator segments 8 in any of the foregoing embodiments. If desired, the members 8 may take the form of pick-up coils and the members 1 and I3 may take the form of coupling coils. Furthermore. if desired, the members 1 and I3 may be in the form of brushes which contact with the successive commutator segments.

It will be understood that the signals applied to member 1 in each of the embodiments are direct current signals. Therefore, if necessary, a separate rectifier may be connected between the receiver 8 and the member 1.

Various changes and modifications may be made in the disclosed embodiments without departing from the spirit and scope of the invention.

What is claimed is:

1. In a direction-tinder system, a rotatable searching pick-up antenna, radio receiver means to detect direction-finder signals picked-up by said antenna, a plurality of electrostatic signal storing elements. a signal indicator of the integrating type, commutator means for charging said storing elements in cyclical succession in synchronism with the rotation of said antenna, and means to couple said storing elements in succession to said indicator to produce an integrated trace of the polar diagram around said antenna.

2. In a direction-finder system, a rotatable polar diagram. a cathode-ray tube havingaseri searching pick-up antenna, radio receiver means of beam deector elements equal in number to detect direction-finder signals picked-up by the number of said condensers, and means to ei said antenna and including means to rectify said ergize said deector members successively by sa signals, a plurality of condensers, a commutator 5 condensers. for charging said condensers in succession in syn- 8. A system according to claim '7 in which sai chronism with the scanning of successive segbeam deilector elements are in the form of elec ments of the polar diagram around said antenna trostatic plates which are directly connected i as it is rotated, a cathode-ray tube indicator, corresponding ones of said condensers. means to rotate the beam of the cathode-ray tube l0 9. A direction-finder system comprising a rc in synchronism with said antenna, and means to tatable direction-finding antenna having a cardi deflect said beam successively under control of oid polar diagram with relation to a distant radi said condensers to reproduce a trace correspondation source, a direction-finding radio receive ingtosaid polar diagram. for producing D. C. signals corresponding suc 3. A direction-lnder system according to claim Cessively to successive sections of said diagram a; 2 in which each of said condensers is shunted by scanned by said antenna, a cathode-ray tube havan individual adjustable discharging circuit. ing a series of four electrostatic beam deectoi 4. A direction-finder system aocordingto claim Plates fOr tracing said diagram. and means t( 2 in which each of said condensers is shunted by charge said plates successively in accordance with a resistor each of said condenser-resistor combithe scanned segments of said diagram, the lastnations having a fast charging path and a slow mentioned means including a set of four storing discharging path condensers connected respectively to correspond- 5. A direction-iinder system according to claim ing Ones 0f said deector plates, and a commuta- 2 in' which the means to rotate the cathode-ray tor for charging said condensers under control of beam comprises a pair of eld coils which are Said D. C. signals and successively in synchronism mechanically rotated in synchronism with the With the rotation of said antenna. rotation of said antenna. Y 10. A directionnder system according `to 6. A directionnndcr system according to claim Claim 9 in which the means fOr Charging said 2 in which the means to rotate the cathode-ray condensers comprises a commutator having a sebeam, comprises a pair of eld coils which are ries of contact segments one for each of said conmechamcally rotated in synchronism with the rodenser-S and a pair of charging brushes mounted tation of said antenna and said rectied signals around Said COmmutatOl. Said brushes being conare applied to said windings to control the beam neted in Parallel to said receiver.

deection. HENRI G. BUSIGNIES 7. A direction-lnder system comprising a rctatable direction-lnder antenna having a direc- REFERENCES CITED tiOnal Dolar diagram With Ielain t0 a distant The following references are of record in the radiation source, a direction-iinder radio receiver me of this patent; for producing D. C. signals corresponding successively to successive sections of said diagram as UNITED STATES PATENTS scanned by said antenna during its rotation, a 9:18a einen .zaqumN plurality of storing condensers, means to charge 2,188,649 Carter Jan. 30, `1940 said condensers successively in synchronism with 2,223,513 Fransson Dec. 3, 1940 the scanning of said successive segments of the 2,403,967 Busignies July 16, 1946 

